The runoff came after Tibilov, 60, fell short of the 50 percent required to win in the first round, with 42.5 percent of votes last month.

A vote "against all candidates" hit 1 percent, with turnout at around 70 percent, RES said.

Sunday's vote marked the third attempt since November to elect a leader amid political turmoil in the region, which Russia recognised as an independent state after driving out Georgian forces during a brief war in 2008.

Electoral commission chief Bella Plieva said no major incidents were reported during the day. "There were some taunts and misunderstandings in polling stations... but the electoral committee reacted quickly and settled them."

"We hope that today our long path to electing a president will be over," Yana Dzhioyeva, a 37-year-old resident of Tskhinvali, South Ossetia's main town, told AFP. "Hopefully, the person who wins will give us a brighter future," she said.

A court annulled the results of a November 27 ballot in which opposition candidate Alla Dzhioyeva beat the expected winner, Anatoly Bibilov, who had open backing from Moscow and the outgoing strongman Eduard Kokoity.

Dzhioyeva then led 10 days of street rallies that ended when Kokoity resigned before his term was due to end.

She was hospitalised in February after being interrogated and allegedly beaten by police amid claims she was planning to seize power by unilaterally inaugurating herself as "president", and did not register for Sunday's vote.

Many people who cast ballots Sunday expressed regret that the November court decision did not permit them to elect a leader that they truly wanted.

Both presidential candidates have denied that they are tied to Kokoity.

Meanwhile, Georgia has called the leadership elections a sham.

"It's a continuation of farce and an imitation of elections in the Russian-occupied ethnically cleansed region," Eka Tkeshelashvili, a minister in charge of reintegration with breakaway regions, told AFP.

About 35,000 people are registered voters at the 84 polling stations in the impoverished region, which relies on financial aid from Russia.

Tskhinvali's streets, which saw much destruction during the 2008 conflict, have remained mostly in disrepair with some construction beginning only this year.

The population of South Ossetia is also the subject of dispute, with the separatist authorities claiming 70,000, but Tbilisi saying the real figure is closer to 15,000 due to migration and what it describes as wartime "ethnic cleansing".

Most South Ossetian residents hold Russian passports and 15,000 also voted in Russia's presidential polls last month. Official reports said 92.7 percent of them voted for president-elect Vladimir Putin.

Russia has recognised the independence of South Ossetia and Abkhazia, another Georgian breakaway region, but other world powers have insisted that both territories remain an integral part of Georgia.